Create reg key with powershell

New-Item "HKLM:\SOFTWARE\Classes\<KEYNAME>" -force
New-Item "HKLM:\SOFTWARE\Classes\<KEYNAME>\shell" -force
New-Item "HKLM:\SOFTWARE\Classes\<KEYNAME>\shell\open" -force
New-Item "HKLM:\SOFTWARE\Classes\<KEYNAME>\shell\open\command" -force

New-ItemProperty -LiteralPath 'HKLM:\SOFTWARE\Classes\<KEYNAME>' -Name '(default)' -Value 'URL:<KEYNAME> Protocol' -PropertyType String -Force
New-ItemProperty -LiteralPath 'HKLM:\SOFTWARE\Classes\<KEYNAME>' -Name 'URL Protocol' -Value '' -PropertyType String -Force
New-ItemProperty -LiteralPath 'HKLM:\SOFTWARE\Classes\<KEYNAME>\shell\open\command' -Name '(default)' -Value 'cmd /K echo %1 > C:\Windows\Temp\param.txt && <YOURSCRIPT_PS1>.ps1' -PropertyType String -Force

Yes i let cmd /K echo %1 > C:\Windows\Temp\param.txt to bypass cmd interpretation on %20 to 0 character (see this post).

Now in run you are able to launch <KEYNAME>://

Note :

HKLM:\SOFTWARE\Classes is equal to HKCR

If you write keys to a key under HKCR, the system stores the information under HKLM\ SOFTWARE\Classes.

References :

• Windows Forums